Bill Barker, the police officer who was swept away when a bridge collapsed in Workington, Cumbria following the severe flooding. Photograph: Cumbria Constabulary/PA

A policeman swept away during devastating flooding was trying to save lives by directing motorists off a bridge across a swollen river.

PC Bill Barker, who would have been 45 tomorrow, was praised by the prime minister, Gordon Brown, as a "very heroic, very brave man".

His body, still in uniform, was found on a beach today. The father of four went missing after a bridge in Workington collapsed amid what the local MP described as the kind of flooding seen only "once every 1,000 years".

Barker went missing when Northside bridge, on one of the main routes into Workington, collapsed at about 4.40am.

It is one of two bridges to have collapsed in the town, where conditions are described as "extremely dangerous" after torrential rain caused rivers to burst their banks.

Cumbria police Chief Constable Craig Mackey said Barker had served with the force for 25 years and described him as "a wonderful police officer and a real family man".

"Bill is a hero who died saving the lives of others and our thoughts are with his family at this devastating time," said Mackey. "He was a much-loved friend, colleague and an inspiration to everyone he knew – he will be sadly missed."

Barker's wife, Hazel, said he was her "best friend, my forever friend, and an amazing dad".

"I have the comfort of knowing that Bill died doing the job he loved, and the fact that he was helping others is just typical Bill," she said. Brown said: "He was a very heroic, very brave man who will be sorely missed by everybody who was close to him.

"I think we owe him a tremendous debt of gratitude for the service he has shown."

Severe flooding has caused the evacuation of hundreds of people in Cumbria, which saw record levels of rainfall. The Environment Agency's gauging station at Seathwaite Farm recorded 314mm in the 24 hours up to 12.45am – a record for England. More than 200 people were forced to leave their homes in Cockermouth. Twenty-five people were still being winched to safety in the area, where both rivers had burst their banks and were running through the town, Cumbria police said.

Chief Superintendent Steve Johnson said: "We currently have helicopters taking people from Derwent Mills, where we have 25 people between the age of 85 and two years of age who have been sheltering there overnight.

"We still can't get to them through the floodwaters so they are now being rescued making use of helicopters.

"Some of them are infirm, some of them are vulnerable and they need medication and they need help."

The armed forces were called in to help emergency services cope. Police said all but 10 properties in Cockermouth had been searched with no further casualties found. Police and armed forces were trying to reach the remaining buildings.

Residents said they feared more rain tonight would bring renewed flooding.

Alan Smith said: "The thing with the River Cocker is it can fall as quickly as it can rise.

"It's come down four feet from last night but the fells are sodden, and if we get any more rain it will just come straight off and into the river and the level will rise again."

The Environment Agency said Cockermouth and Keswick had been hit the hardest. Its Floodline service has received more than 12,000 calls from members of the public over the last 48 hours and issued more than 43,000 flood alerts via phone, text, email and fax.

"We have seen unprecedented rainfall, with what we believe is a record amount for a 24-hour period in England," said the agency chairman, Lord Smith. "Towns and villages across Cumbria have been evacuated with floodwater driven by heavy rainfall, saturated ground and swollen rivers."

The Workington MP, Tony Cunningham, said the flooding was "of biblical proportions" and on a scale seen "once every 1,000 years".

He told Sky News: "The scale and the force of the devastation in Cockermouth is huge.

"I went down to the bridge last night and I've never seen the river Derwent as wide as it was. The force of the river was absolutely incredible. This is a stone bridge; to wash away a bridge of that size and dimension is incredible."

Emergency 999 calls made from some flood-hit areas were not getting through, the police said. People in Workington, Cleator Moor and Harrington were advised to call 0845 330 0247 to reach all emergency services. Police have opened a casualty bureau to deal with concerned members of the public seeking news of friends and relatives. People are advised to call 0800 056 0944 or 0207 158 0010.